1. Field of the invention
This invention relates to control devices for pick-up arms of record players.
2. Discussion of the prior art
It is known for a control device for a pick-up arm of a record player, particularly an automatic record player, to include a drive mechanism for moving the pick-up arm and clutch means by means of which the drive mechanism can be connected to or disconnected from the pick-up arm.
In addition to a facility for manual operation, it is desirable for a record player to have means for automatic control of the movements of its pick-up or tone arm. This means in particular that the pick-up arm should be controllable so that it can be set into any desired position. With high quality record players in particular, it is highly desirable that the pick-up arm, after it has been moved to a desired position for playing the record, be disconnected completely from the drive mechanism which produced the movement. This is to ensure that the very small amount of friction produced by the means mounting the pick-up arm during the course of playing is not increased by the drive mechanism remaining coupled to the arms. In addition, great demands are made in high-quality record players on the evenness of the movement of the pick-up arm. It should also be possible to interrupt the movement of the pick-up arm at any time and at any desired point without jerking or "run-on", i.e. movement after the arm should have come to a halt resulting in "overshooting" .
There are known control devices in which movement of the pick-up arm by the drive mechanism is forced to run through a specific programmed cycle. Record players incorporating such control devices are on the market. There are also record players on the market which have one or more separate motors for driving the pick-up arm and permit manual, semiautomatic or fully automatic playing of records. However, these known record players do not afford any great evenness in the movement of the pick-up arm. Further, in these record players the tone arm can be stopped at a desired point with only a low degree of accuracy, unless fixed mechanical stops are provided for the purpose, like those which are also known in record players.
Record players with a linear movement of the pick-up arm, i.e. with a linear pick-up arm, are also known, the point of rotation of the arm lying on a linearly moving and therefore not a stationary spindle. In such a record player, with each change of position of the pick-up system the point of rotation of the pick-up arm must be displaced by the amount of this change. The mechanical structure required for this necessitates a precision carriage guide, and substantial expenditure on a linear follower control means is necessary.